Intro to Scientific Computing PHYS 27/193 Physics Department University of the Pacific

Learning More About Emacs

Command	Action
At xterm prompt: emacs -nw file	Open file in emacs
In Emacs: C-x C-f	Find (Open) File for editting
In Emacs: C-x C-s	Save Buffer to File
In Emacs: C-x C-c	Quit Emacs

Of course we'd like a little more functionality.

Recall that C-x means CTRL-x. There are many commands which take the form C-some key.

And, there is another type of command that we haven't yet used yet (I mentioned it on the previous page).
These are commands that take the form

ESC-key  this is abreviated M-key

The reason these commands are abreviated M-key is that M stands for Meta, which comes from the days before keyboards were standarized. Now, the dust has settled and M stands for ESC, the Escape key. This key is a prefix key--you his Esc then another key, as opposed to the Ctrl key which is a modifier--you hold CTRL down while you press another key.

Playing with Emacs

Let's learn a bit more about Emacs.

On the previous pages I had you start emacs with the command: emacs -nw  which opens emacs in an xterm window in text (no GUI window) mode.
Now let's open emacs in GUI mode. Open an xterm and at the prompt type:

emacs

Just emacs, no -nw.

This will open an emacs window on your screen that looks like this:

Notice that GUI version has the same four areas as the text mode version:

• the toolbar
• the buffer area
• the mode line
• the mini-buffer

Let's open a file to play with. We're going to open it a couple of different ways.

First, click on the File menu on the Toolbar.

Click on "Open File...".

You might expect this to open a GUI window that allows you to click on the file you want.
What happens however, is that the text: "Find file: ~/" in the mini-buffer.
What you do is type the name of the file that you want to edit in the mini-buffer. Emacs puts the name of the current directory after the "Find File:".

Before we open a file, let's Abort this Find File. This is a very useful thing to know how to do.

In the Emacs window, type C-g (CTRL-g)

The mini-buffer says "Quit". This is because we Aborted the command to Find a File.
In general, you can always abort whatever you are doing (or were trying to do).

Now click on the Find File Icon:

The same thing happens as before: "Find File:..." appears in the mini-buffer.

Abort this with C-g

Finally, you can open the file using the method you already know!--the text sequence mode we used before. This is the method to use when connected to a computer over the network. In the emacs window, type:

C-x C-f

Same thing: you get "Find File:" in the mini-buffer.

This time let's open a file.

If you type the name of a file which does not exist, the buffer is renamed to this name, and the words (New File> appears in the mini-buffer.

Go ahead and type the name of a new file: zzz

Do you see the (New File) text in the mini-buffer?

Now type some characters in the buffer window. Anything will do.

Let's not save this file. We can Kill the buffer by clicking on the X in the Tool Icons.

This brings up a dialog window that asks you: Buffer ... modified; kill anyway? [Yes] [No]

Click [No].

Now let's do the same via text-based commands. In the emacs window, where you still have the new zzz buffer, type:

C-x k

This is CTRL-x followed by typing the key k.

The mini-buffer should say: Kill buffer: (default zzz)

Type ENTER

The mini-buffer will respond with: Buffer zzz modified; kill anyway? (yes or no)

With the cursor at the right end of the mini-buffer (click on the end of this text if it's not there already).

type: yes

The zzz buffer should disappear.

Let's summarize:

To open a file  (find-file)

To kill a buffer  (kill-buffer)

So now let's step up the pace a bit.

Your emacs window should still be open. Go ahead and close it (quit). Remember how?

Now cd to your home dir and make a new subdirectory called editplay/.
Cd to editplay/.
Now save the following file into this directory:

stairway.txt

Open it in emacs (use the GUI version of emacs), by typing emacs stairway.txt

Movement

In graphical GUI mode, things work pretty much as you would expect from other word processors like MS Word:

in Window Mode (GUI)

Most normal movement cammands work:

• Right, Left, Up, Down Arrows
• Page Up, Page Down
• Home, End
• and the Scroll Bar on the left side

In text mode movement can be achieved with the same keys usually, but sometimes on a remote machine the terminal emulation can be strange. For this reason, emacs has some text-based key strokes which implement movement commands. These are

in Text Mode

C-a	Beginning of line
M-f	Forward one word
M-a	Previous sentence
M-v	Previous screen
M-<	Beginning of buffer
C-e	End of line
M-b	Back one word
M-e	Next sentence
C-v	Next screen
M->	End of buffer

Notice that the GUI mode of Emacs recognizes all the Text-Based commands as well. In fact, I work with emacs over a network connection so often that when I am in GUI mode, I still use the text-based versions of most commands.

Try the text-based movement commands above

Remember that M-f (for example) means ESC f.

Cutting and Pasting

In your open "stairway.txt" buffer,
Click/drag your mouse in the text to highlight a region of text as shown below.
(pick one of the stanzas of the song)

In Emacs lingo this highlighted area is called  The Region.
We'll come back to this concept in a minute.

With the region still highlighted,

click the Edit menu item on the Toolbar,
then click Cut

The highlighted region should disappear. This is the same as CTRL-x in MS Word. You have "Cut" the region of text, and at the same time Copied the region to the Clipboard.

Now go to the Toolbar and

click Edit->Paste.

This should put back the text you just "Cut". It will be Pasted at the place where the cursor is located.

Notice too that under Edit you also have the option to Undo your changes.

Try this:

Highlight some text again
Cut the text by doing: Edit->Cut
Undo your "Cut" by clicking: Edit->Undo

This should put back the text you Cut.

Now let's try this in

Text mode

This is how you cut/copy text when you are editing using emacs on a remote machine via a text terminal.
We can still issue the key sequences in the open emacs window; it will respond the same way.

In your open emacs window,

move the cursor to the beginning of a stanza of the song.

Preferrably do this with the arrow keys as you would in an xtext window.

Now, Set the Mark, by typing

C-spacebar

The words Mark set will appear in the mini-buffer.

The Region is now the area between the Mark and the Cursor.
Having set the Mark at the beginning of the stanza,

move the cursor to end of the stanza

Now type

C-w

This is the text-mode key sequence that does "Cut".

Similarly, the text-mode key sequence to "Copy" is M-w (ESC w).

The text-mode key sequence to Undo is

C-x u

Try this now. Does the text you "Cut" come back (i.e. was your "Cut" undone)?

Pasting

In GUI mode, pasting the text you just cut is easy. Highlight the text, click Edit->Cut, put the cursor where you want it and click Edit->Paste. Pretty easy.

In Text-Mode, the Paste command is C-y ("y" for yank).

Go back and "Cut" a stanza again:

Move the cursor back to the beginning of the stanza
Set the Mark, with C-spacebar
Move the cursor to the end of the stanza
Type C-w

This has just "Cut" some text, as we did above.
To "Paste" the text, move the cursor to the place you want to paste it, then type:

C-y

This should "Paste" the text you just "Cut" at that point.

Let's summarize Cutting and Pasting:

Cut Text  (kill-region)

Copy Text  (kill-region)

Paste Text  (yank)

Summary

Startup

GUI-mode	Text-mode	Action
at the prompt: emacs file	emacs -nw file	Open file in emacs

Open/Close Files

GUI-mode	Text-mode	Action
File->Open File...	C-x C-f	Find (Open) File for editting
File->Save Buffer As...	C-x C-s	Save Buffer to File
File->Exit Emacs	C-x C-c	Quit Emacs
File->Close Current Buffer	C-x k	Close (Kill) Buffer

Movement

GUI-mode	Text-mode	Action
Home	C-a	Beginning of line
	M-f	Forward one word
	M-a	Previous sentence
PgUp	M-v	Previous screen
	M-<	Beginning of buffer
End	C-e	End of line
	M-b	Back one word
	M-e	Next sentence
PgDn	C-v	Next screen
	M->	End of buffer

Notice that there are several more text based commands for moving around. Learning these can make you quit fast in the editor.

Cut/Copy/Paste

GUI-mode	Text-mode	Action
Highlight text; Edit->Cut	Set Region with Mark (C-space) and Cursor; C-w	Cut
Highlight text; Edit->Copy	Set Region with Mark (C-space) and Cursor; M-w	Copy
Edit->Paste	C-y	Paste